Serum complement level in dengue hemorrhagic fever.

To elucidate the immunpathological changes occuring in the clinical course of hemorrhagic fever, the activity of complement and of all nine of its components activities were measured with 64 samples. These serum samples were collected from 10 cases of hemorrhagic fever with shock and 4 cases of hemorrhagic fever without shock on different days of illness. Depression of complement activity in acute phase as compared with that in the reconvalescent phase was observed in the following cases. Eight cases out of 10 of hemorrhagic shock patients showed depression of hemolytic activity of the whole complement while 3 out of 4 patients without shock showed depression. The C3 activities showed a characteristic pattern. Nine out of 10 patients with shock and 2 out 4 patients without shock showed depression on the acute phase. As for the whole complement activity in immune adherence and C4 component activities in the serum, depression in the acute phase was observed to some extent and they showed good correlation. Essentially no significant changes were observed with C1, C2, C5, C6, C7, C8 and C9 activities. Significance of the change of C3 level in clinical manifestation of immunopathological process was discussed in relation to the function and molecular structure of C3.